1. Field of the Invention
This invention relates to a raw material powder for a laser clad valve seat superior in productivity, cladding property, wear resistance, and finishing property, and also relates to a valve seat using this raw material powder.
2. Background Art
Conventionally, Fe based powder sintered materials are mainly used for valve seats employed in vehicle engines or the like. The valve seat is pressed into the cylinder head to inhibit a wear caused by the valve. In recent years, there have been suggested techniques for a laser clad valve seat of a copper alloy having a radiating property and a thin-wall property superior to those of such a sintered valve seat, as is described in the following documents, for example.
Japanese Patent Laid-Open Publication No. 162100/2004 discloses a cladding copper alloy powder comprising, by weight, 8.0 to 20.0% of Ni, 1.5 to 4.5% of Si, a total of 2.0 to 15.0% of at least one of Fe, Co and Cr, and a total of 0.1 to 1.5% of at least one of Mm (Misch metal), P and Ti, with the balance Cu and unavoidable impurities.
Japanese Patent Publication No. 942/1996 discloses a dispersion strengthened Cu based alloy superior in wear resistance, comprising, by weight, 5 to 30% of Ni, 1 to 5% of Si, 0.5 to 3% of B, and 4 to 30% of Fe, with the balance Cu and unavoidable impurities, and having a structure such that particles of Fe—Ni based silicide and boride are dispersed in a Cu based matrix.
Japanese Patent Publication No. 2748717 discloses a cladding, wear-resistant, copper based alloy comprising, by weight, 10 to 30% of Ni, 1 to 5% of Si, and 2 to 15% of Fe with the balance Cu and unavoidable impurities and having a structure such that a hard layer of Fe—Ni based silicide is finely dispersed in a Cu—Ni alloy having uniformly fine dendrite.
However, none of the alloys disclosed in the documents exhibits satisfactory wear resistance, even in particular use under environments where adhesive wear is apt to occur intensively, nor it indicates superior performance in productivity, cladding property, and finishing property.